A Flash Flood Warning is in effect right now for Mercer, Bergen, Warren, Camden, Essex, and Middlesex counties in New Jersey. The warning was issued by the National Weather Service Mount Holly NJ and NWS Upton NY at 5:13 PM EDT on August 27, 2026, and remains active until 6:15 PM EDT on August 27, 2026. If you are in any of these counties at the time you read this, treat the warning as current until you confirm it has expired through official NWS channels.
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These six counties span a wide geographic spread across the state, from the Delaware River corridor in Warren and Mercer to the densely populated suburban and urban areas of Bergen, Essex, Camden, and Middlesex. Flash flooding can develop and intensify within minutes, and conditions across all six counties should be treated as actively dangerous until the warning expires.
What the National Weather Service Is Telling You to Do Right Now
The official instruction from the National Weather Service is direct and unambiguous: turn around, don’t drown when you encounter a flooded road. The NWS emphasizes that most flood deaths occur in vehicles, not in homes or on foot. That single data point reshapes how you should think about your immediate decisions.
A flooded road does not need to look dramatic to be lethal. Six inches of moving water can knock a person down. Two feet of water is enough to carry most passenger vehicles off the road surface entirely. The problem is that drivers routinely underestimate the depth of water on a road because the surface still appears solid beneath it. The current is invisible from a driver’s seat. The NWS warning exists precisely because that visual gap between what a road looks like and what it can do to a vehicle kills people every flooding season.
If you are driving in Mercer, Bergen, Warren, Camden, Essex, or Middlesex County right now and you reach a road covered by water, the NWS instruction is not a suggestion to use your best judgment. It is a directive to stop and turn around. Do not attempt to cross, regardless of how shallow the water appears, how many other vehicles are crossing, or how familiar you are with that road under normal conditions. Find an alternate route or wait the warning out at a safe location away from the roadway.
If you are already home or at a stationary location, stay there. The window on this warning is short, expiring at 6:15 PM EDT on August 27, 2026. Avoiding travel during that window costs far less than the alternative.
How This Fits the Broader Picture for New Jersey Residents
Flash flood warnings like this one are short-fuse events, meaning they develop and close quickly, but they reveal a preparedness gap that lasts year-round. The vehicles-as-primary-risk finding from the NWS is consistent across flood events nationwide, yet it remains one of the least internalized facts among drivers. Building the habit of treating any water over a roadway as a hard stop, not an obstacle to assess, is the practical takeaway that carries past this warning window. USRiskRadar.com covers the full range of flash flood preparedness guidance in our flood resources section for readers who want to build a household plan that accounts for this risk before the next warning is issued.
For the fundamentals that apply beyond this specific alert, see our Flood Preparedness guide.
Source: National Weather Service (NWS Mount Holly NJ, NWS Upton NY). Active alert data retrieved 2026-08-27 22:01 UTC via api.weather.gov.
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